Available online at www.jourcc.com Journal homepage: www.JOURCC.com Journal of Composites and Compounds Journal of Composites and Compounds 2 (2020) 123-128 Ni-Cu matrix composite reinforced with CNTs: preparation, characterization, wear and corrosion behavior, inhibitory efects Morteza Ferdosi Heragh a , Sara Eskandarinezhad b *, Alireza Dehghan c a Faculty of Materials and Metallurgical Engineering, Semnan University b Department of Mining and Metallurgical Engineering, Yazd University, Yazd, Iran c Department of Research and Development, Applied research center of the geological survey of Iran, Alborz, Iran * Corresponding author: Sara Eskandarinezhad; E-mail: s.eskandari.nezhad@gmail.com https://doi.org/10.29252/jcc.2.3.3 This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0) 1. Introduction St37 steel is structural steel available in various forms. This type of steel is inexpensive and can be used in diferent applications including plant fabrication, piping, etc. Carbon is the main alloying element in the steel and there are some trace impurities as well. The hardness and strength of the steel are enhanced with the increment of the carbon con- tent [1-4]. As steel and its alloys are extensively utilized in industrial components, their protection against acid electrolytes and their corro- sive efect is necessary [5-7]. Common protection methods are alloying steel with inhibiting elements, using corrosion inhibitors, cathodic and anodic protection, and protective coatings [8, 9]. In various applications like the automotive and aerospace industry, composite coatings prepared via co-deposition of small reinforcement particles into a metal matrix are extensively used [10, 11]. It has been reported that the composite coatings could enhance microhardness, high-temperature stability, wear resistance, and corrosion resistance of metal and alloy. There are sever- al factors that should be considered in selecting these coatings such as technical constraints, environmental pollution, costs, simplicity of the coating process [12-15]. In the marine environment, Ni-Cu alloys, particularly alloy that con- tain about 70%, Ni shows high corrosion resistance. Apart from corro- sion resistance, solderability, ductility, and malleability are other attrac- tive features. Cu and Ni have the standard reduction potentials of +0.34 V and 0.25 V vs. a normal electrode of hydrogen (NHE), respectively, which are disparate to some extent. A normal co-deposition of Ni and Cu is the plating process of Ni-Cu alloy. The incorporation of Cu in Ni strengthens it owing to the formation of a solid solution that enhances wear and corrosion resistance [16]. Besides the selection of the coating method, optimization of the elec- troplating method and the alloying system is also necessary. Some appli- cable techniques include electrodeposition, physical vapor deposition, chemical vapor deposition, plasma spraying, and thermal spraying. For the preparation of Ni coatings, electrodeposition has been reported to be a proper technique [17]. The reduction of the corrosion rate could occur in the alloy by adding metallic (e.g., Cr, or Mo) or nonmetallic (e.g., P, N or Si) inhibiting components, which forms adsorbed intermediate products on the alloy surface and blocks the active areas [8]. Since their emergence, carbon nanotubes (CNTs) have been in- creasingly used for the fabrication of advanced composites as the ideal reinforcing agent owing to their rewarding mechanical properties such as fracture strain sustaining capability, light weight, large elastic strain, and high elastic modulus [18-20]. However, CNT-containing composite applications are accompanied by the high complexity because several factors such as the nanotube/matrix bonding, nanotubes dispersion, rein- forcement aspect ratio, surface reactivity, and densifcation of bulk com- posites should be controlled [8, 21-23]. In this research, the Ni-Cu/CNT composite coating is deposited on the st37 substrate, and its mechanical and corrosion behaviors as well as the inhibitory property of CNT on the coating surface were evaluated. A B S T R A C T A R T I C L E I N F O R M A T I O N St37 steel has been used in various industries due to its abundance and low cost. However, the high corrosion rate of steel in acidic environments is one of the limiting factors for its application. In this study, Ni-Cu compos- ite coating reinforced with CNTs was applied on the st37 steel substrate. The extract of the Sarang Semut plant was added to the coating as inhibitory particles and the electrochemical behavior of the coating was investigated. The X-ray difraction test was performed for phase analysis. Hardness, wear, and dynamic potential polarization tests were performed. Results showed that the presence of CNT particles improved the hardness, tribological performance, and electrochemical behavior of the coating. Also, the presence of Sarang Semut particles acted as a barrier and protected the surface of st37 steel from corrosion. It should be noted that these particles afected the kinetics and thermodynamics of corrosion reactions and were not involved in the reactions. ©2020 jourcc. All rights reserved. Peer review under responsibility of jourcc Article history: Received 18 August 2020 Received in revised form 13 September 2020 Accepted 17 September 2020 Keywords: St37 Corrosion resistance CNTs Ni-Cu composite coating